Dear All,
The authors of the following paper used molecular replacement of the substructure to locate the heavy atoms. The known 11-fold symmetry meant that the heavy atoms had to be in a circle - molecular replacement with circles of different radii did the trick. Antson et al. Nature, Vol. 374 (1995), pp. 693-700. You simply need to use the DANO field of the mtz instead of the intensities if using anomalous data. I have found the known Se substructure by molecular replacement this way as a proof-of-principle (after finding the substructure with shelxd). Whether molecular replacement of the substructure is in general a useful thing to do is another question, modern software is extremely good at locating heavy atom sites. James Dr. James Murray Biochemistry Building Department of Biological Sciences Imperial College London London, SW7 2AZ Tel: +44 (0)20 7594 5276 Dr. James Murray Biochemistry Building Department of Biological Sciences Imperial College London London, SW7 2AZ Tel: +44 (0)20 7594 5276